Valve Material Reference
ASTM A351 HH Valve
25Cr-12Ni Heat-Resistant Casting (Grade HH)ASTM A351 Grade HH is a high-chromium, high-nickel heat-resistant cast alloy used for valve bodies and components in very high-temperature service — furnace applications, petrochemical cracking, and catalytic reformer internals.
Form
Cast
Max Temp
+1,100°C (+2,012°F)
Min Temp
−10°C (not for cryogenic service)
Category
Stainless Steel
Chemical Composition — ASTM A351 HH
Temperature Range
Up to +1,100°C (+2,012°F) — continuous service; +1,150°C intermittent
Maximum Temperature
+1,100°C (+2,012°F)
Minimum Temperature
−10°C (not for cryogenic service)
Equivalent Grades — ASTM A351 HH
| Standard | Equivalent Grade |
|---|---|
| ASTM | A351 HH (cast) |
| ASTM Forged | A182 F310 / A276 TP310 (wrought equivalent) |
| DIN | GX40CrNi25-12 / 1.4826 |
| BS | BS 3100 Grade 302 C35 |
Suitable Services
Fluid catalytic cracking (FCC) regenerator circuit — temperatures 680–750°C, sulphur + catalyst dust
Catalytic reformer outlet manifolds — temperatures 500–550°C, H₂-rich atmosphere
Sulphur plant Claus converter outlet — temperatures 300–600°C, H₂S + SO₂ + liquid sulphur
Ethylene cracker quench circuit valves — pyrolysis gas at 800–1,000°C quenched to 400°C
Not Suitable For
Cryogenic or low-temperature service — brittle below −10°C
Aqueous chloride service — austenitic SS with high Ni/Cr can suffer SCC under stress and chlorides
Standard steam or water service — overspecified and expensive; A216 WCB is adequate
Valve Body Applications
FCC regenerator valves — slide valves, plug valves, and transfer line valves
Fired heater outlet valve bodies for crude, vacuum, and thermal cracking services
Reformer outlet manifold and header valves (very high-temperature H₂ service)
Sulphur recovery unit (SRU) Claus plant high-temperature air and gas valves
Trim Applications
Seat rings and discs for extreme-temperature globe and gate valves
Stem material for very high-temperature valve applications
Typical Valve Types in ASTM A351 HH
Gate valves
Globe valves
Slide valves (FCC)
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We supply ASTM A351 HH (25Cr-12Ni Heat-Resistant Casting (Grade HH)) gate valves, globe valves, ball valves, check valves, and more. Full certification documentation — EN 10204 3.1/3.2 MTCs, hydro test certs — as standard.